ISRO CS 2020

Question 21

What is the complexity of the following code ?

sum = 0;
  for (i = 1; i <= n; i*= 2)
    for(j = 1; j <= n; j++)
      sum++; 

Which of the following is not a valid string ?

• Ο(n²)
• Ο(n log n)
• Ο(n)
• Ο(n log n log n)

Question 22

In the following procedure

Integer procedure P(X, Y);
Integer X,Y:
value x;
begin
  K = 5;
  L = 8;
  P = x + y;
end 

X is called by value and Y is called by name. If the procedure were invoked by the following program fragment

K = 0;
  L = 0;
  Z = P(K, L); 

then the value Z would be set equal to

• 5
• 8
• 13
• 0

Question 23

Consider product of three matrices M1, M2 and M3 having w rows and x columns, x rows and y columns, and y rows and z columns. Under what condition will it take less time to compute the product as (M1M2)M3 than to compute M1(M2M3) ?

• Always take the same time
• (1/x + 1/z) < (1/w + 1/y)
  
• x > y
• (w + x) > (y + z)

Question 24

A new flip flop with inputs X and Y, has the following property. Which of the following expresses the next state in terms of X, Y, current state ?

• X\'Q\' + Y\'Q
• X\'Q + Y\'Q\'
• XQ\' + YQ
• XQ\' + Y\'Q

Question 25

What is the output of the following ‘c’ code assuming it runs on a byte addressed little endian machine?

C

#include <stdio.h>
int main( )
 {
   int x; char *ptr;
   x = 622,100,101;
   printf(\"%d\", (*(char *)&x) * (x % 3));
   return 0;
 } 

• 622
• 311
• 22
• 110

Question 26

What is the output in a 32 bit machine with 32 bit compiler ?

C

#include <stdio.h>

rer(int **ptr2, int **ptr1)
 {
  int* ii;
  ii = *ptr2;
  *ptr2 = *ptr1;
  *ptr1 = ii;
  **ptr1 *= **ptr2;
  **ptr2 += **ptr1;
 }
void main( )
 {
   int var1 = 5, var2 = 10;
   int *ptr1 = &var1, *ptr2 = &var2;
   rer(&ptr1, &ptr2);
   printf(“%d %d “, var2, var1);
 } 

• 60 70
• 50 50
• 50 60
• 60 50

Question 27

Which of the following is an efficient method of cache updating ?

• Snoopy writes
• Write through
• Write within
• Buffered write

Question 28

In a columnar transposition cipher, the plain text is “the tomato is a plant in the night shade family”, keyword is “TOMATO”. The cipher text is

• “TINESAX / EOAHTFX / HTLTHEY / MAIIAIX / TAPNGDL / OSTNHMX”
• “TINESAX / EOAHTFX / MAIIAIX / HTLTHEY / TAPNGDL / OSTNHMX”
• “TINESAX / EOAHTFX / HTLTHEY / MAIIAIX / OSTNHMX / TAPNGDL”
• “EOAHTFX / TINESAX / HTLTHEY / MAIIAIX / TAPNGDL / OSTNHMX”

Question 29

Avalanche effect in cryptography refers

• Large changes in cipher text when the keyword is changed minimally
• Large changes in cipher text when the plain text is changed
• Large impact of keyword change to length of the cipher text
• None of the above

Question 30

A magnetic disk has 100 cylinders, each with 10 tracks of 10 sectors. If each sector contains 128 Bytes, what is the maximum capacity of the disk in kilobytes ?

• 1,280,000
• 1280
• 1250
• 128,000